Interventional neurologists use minimally invasive techniques to treat a variety of diseases. In the Brain and Spine Tumor Program, interventionalists perform several procedures that support the treatment of neurological cancers.
Pre-Operative Brain Tumor Embolization
Surgically removing a brain or spine tumor often requires cutting through the blood vessels that supply the tumor. This can lead to significant bleeding. To help reduce bleeding during surgery, interventional neurologists often perform pre-operative tumor embolization, a procedure that cuts off the tumor blood supply prior to tumor removal.
The tumor embolization procedure usually takes place the day before surgery or the morning of the operation. First, diagnostic angiography is used to identify the blood vessels that supply the tumor. The interventional neurologist then inserts a catheter device into the patient’s femoral artery (near the groin) and uses imaging guidance to advance the device through the blood vessels to the brain. Next, digital subtraction angiography is used to image the blood vessels around the tumor site.
The interventional neurologist then injects micro-particles of poly-vinyl alcohol through the catheter into the capillary bed of key tumor blood vessels. The particles clump together, forming a dam that cuts off the blood supply to the tumor. During a typical procedure, the interventionalist will embolize from two to six arteries. The goal is to de-vascularize as much of the tumor as possible.
Cutting off a tumor’s blood supply results in a safer tumor removal surgery with less blood loss and a shorter operation time. Embolization often enables surgeons to remove more tumor tissue with less risk.
Arterial Test Occlusion
Some brain tumors cannot be removed without sacrificing a large artery (for example, the carotid artery or a vertebral artery). The risk is that removing this blood supply will damage important areas of function within the brain. In these situations, interventional neurologists perform a procedure that tests the importance of specific arteries.
Using a catheter, the interventional neurologist guides a balloon device to the site of the artery in question. The balloon is then inflated, temporarily occluding (blocking) the artery and cutting off the flow of blood. The patient then undergoes a variety of tests to evaluate the effect of the blockage on his or her speech, vision, strength and other abilities.
At the same time, angiography or SPECT imaging is used to evaluate the flow of blood through collateral blood vessels within the brain (“alternative routes” through the brain’s vascular system). During an arterial test occlusion, the balloon remains inflated for approximately 30 minutes. In many cases, testing reveals that the artery in question is not critical for maintaining brain function. In these instances, the interventional neurologist will often perform a permanent occlusion immediately to prevent bleeding problems during surgery.
When a tumor is very close to regions of the brain that control language or memory, interventional neurologists can perform a Wada Test to precisely locate these areas of function. A catheter device is used to inject sodium amytal into an artery that feeds the area of interest, temporarily anesthetizing a small section of the brain. The patient then undergoes a series of tests to assess his or her language skills (such as repeating sentences and naming objects shown in pictures) and memory skills (through short-term memory exercises).
The patient’s performance on a Wada Test shows whether or not language and memory live in the area of the brain being considered for surgical removal. This helps the care team develop a surgical plan that offers a lower risk of impairment. Wada testing is also used to help plan epilepsy surgeries.
Radiofrequency Ablation (RFA) for Spine Tumors
Metastatic tumors within the bony spine can cause significant pain when they press against the spinal cord. Many of these spine metastases cannot be removed surgically. In these situations, interventional radiologists can perform a minimally invasive procedure that destroys the metastatic tumor with heat energy. Using image guidance, a radiofrequency probe is inserted into the spine and positioned at the tumor. When activated, the probe emits radiofrequency waves that heat and kill tumor cells.
Treatment of Spine Compression Fractures
Metastatic tumors in the spine can also weaken the vertebrae, leading to painful fractures. Interventional neurologists offer two procedures to treat this condition:
Vertebroplasty. Using imaging guidance, a special cement is injected into the fractured vertebra. The cement seals the fracture and restores the stability of the bone. For some patients, pain goes away within 24 hours.
Kyphoplasty. A special balloon is introduced into the fractured vertebra. The balloon is then inflated and filled with special cement, stabilizing the bone and providing significant pain relief.